Electric discharge device and operating circuits therefor



w. WILSON. ELECTRIC DISCHARGE DEVICE AND OPERATING CIRCUITS THEREFOR.

APPLICATION FILED MAR- 30,19I8- Patented Jan. 17, 1922..

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WILLIAM WILSON, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC 'I'RICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Jan. 1'7, 1922.

Application filed March 30, 1918. Serial No. 225,682.

To all whom it may colwem:

Be it known that I, WILLIAM WILSON, a subject of the King of Great Britain, resid ing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Electric Discharge Devices and Operating Circuits Therefor, of which the following is a full, clear, concise, and exact description.

This invention relates to electric discharge devices and operating circuits therefor which are particularly applicable for use in signaling circuits.

An object of this invention is to provide a novel type of an electric discharge device capable of being employed for repeatlng or amplifying signals, particularly when selective amplification or repeating is desired.

A further object of this invention is to provide a' vacuum tube capable of functioning both as an annunciator and as a repeater of electric waves, whereby an impulse impressed on the tube will cause it to be energized so as to function as an annunclator, after which the tube may serve as a repeater of the incoming signals.

As is well known in the art an evacuated vessel of the audion type comprises three electrodes, a filament, an anode and an auxiliary electrode. In one form of this invention, in addition to these electrodes is provided a floating electrode between the auxiliary electrode and the filament, whereby the space current between the filament and the anode is made independent of the static potential, or of slow changes of the potential of the auxiliary electrode of the order of one cycle per second, but is dependent upon rapid changes of the potential of said electrode due to voltages of a higher frequency such as voice or radio frequencies. This structure as above described is therefore particularly adapted for a system for the reception of signals, since the space current of the vessel in each arrangement may be varied in accordance with rapidly varying impulses impressed thereon,that is, its response for such frequencies is quantitative, and so the vessel may be employed as a repeater of incomin signals; and alsosince the space current is independent of slowly varying impulses,that is, since the vessel respon s qualitatively only to such low frequencies, a vessel having normally zero space current may have'its current flow started by a single impulse, which current will continue to pulses follow the initial impulse, so that the arrangement is also' adapted to serve as an annunciator to energize a relay for ringing a bell, for example.

Although this vacuum tube annunciator will hereinafter be described in connection with a receiving station for a high frequency signaling system, it is to be understood that it also may be employed for all other purppseds to which an annunciator may be app 1e For the setting of the tube for the'annun ci'ator action, the potentialof the grid is made just below the critical value for no space current, thereby making the space current substantially zero. An incoming positive impulse of any frequency which would, for instance, be a component part of an incoming signal wave impressed upon the grid will start the space current which will thereafter persist and be independent in value of slow changes of potential of the grid. The current, which is thereby established in the output circuit may be employed to energize a relay for ringing a bell, or to energize any other apparatus desired after the space current flow has been established by an incoming impulse. The same tube when the space current has been established is then in condition to be employed as an amplifier or detector of the incoming signal oscillations, as for rapidly varying oscilla: tions the operation of the tube has been flow irrespective of whether other im v found to be substantially the same as if the in addition to the usual filament 6, anode 7 I and control electrode 8, is a fourth electrode 9 which is floating,'that is, insulated from the other electrodes 10 and 11 are the leading-in conductors for the filament, and 12 and 13 are the leads respectively for the anode and control electrode. It is to be noted that no leading-in conductor is no vided for the floating electrode. Fi 2 i lustrates a receiving system for highrequenc signaling, having in commie-tion therewit a vacuum tube annunciator of the general form shown in Fig. 1. Assume that the potential of the source of voltage 16 is sufiicient to establish a space current between the anode 7 and the filament 6. If, now, the negative potential of a source of voltage 17 is numerically greater than the critical value for no space current, then, on closing the key 19, the negative voltage applied to the grid will reduce the space current to zero. The tube 5 is then ready to act both as an amplifier and as an annunciator for the signals received by the antenna 20. Assumin that these signals consist of high or' ra io fre uency oscillations, modulated by low or te ephone freqiiency signals, the oscillations received by -t e trans ormer 25 will be impressed upon the circuit 26, tuned to the frequency of the carrier wave oscillations. The oscillations in this tuned circuit are then impressed u on the input terminals of a detector 28. he detected currents in the output circuit 29 by transformer 30 may then be impressed upon the input circuit 32 of the tube 5. These detected currents impressed upon the control electrode will make it more positive than the critical value for no space current, thereby allowing the current to flow. After the space current has been started in such a manner by impressing positive impulses on the control electrode, 1t has been found that the current rises to approximately the value it would have for zero potential of the control electrode, and thereafter remains independent of the value of the static potential of said electrode. The current, however, may be controlled by the ra idly varying impulses resulting from the etection of the incoming signals, so that the tube may function as an amplifier ofthese im ulses.

The space current established in the output circuit 34 by the incoming signals may be employed to energize a relay 35, whereby contact is made between the arm 36 and the point 37 thereby closing the circuit containing battery 39 and the bell 40. The ringing of this bell is therefore, an indication that signals are being received by the antenna. v

The output circuit also contains the detected currents which have been amplified by the tube in a manner now wellknown in art. These amplified oscillations may be impressed by the transformer 42 upon other amplifiers, or as shown, may be impressed upon a suitable receiver 43. As relay 35 presents a path of high impedance for the amplifying currents in the output circuit, a. low impedance path containlng a condenser 45 is shunted around the relay.

In order'to sensitize the annunciator for another call, the space current should be brought to zero a ain. This may be accomplished by opening the key 19 for a short interval of time and then closing it. The theory of operation of the above de scribed system is not at present well under stood. It is probable, however, that the action may be explained on the ground that while the space current is flowing in the tube 5, the floating electrode picks up positive charges of such an amount as to shield the filament from the steady potential of the grid. The thermionic current persists 85 and is thus made independent of the potential between the filament and the control electrode. .When, however, the input circuit is opened for an interval of time sufficient to allow these charges to leak off this floating electrode, then, on closing the circuit again, the input electrode will be brought suddenly to a negative potential greater than that required for no space current and the current is reduced'before the compensating charges have time to collect on the floatingelectrode. But as soon as the grid is momentarily made more positive than the critical value, then the space current will start to flow again and the floatmgi electrode will acquire positive charges su clent to compensate for the static potential between the filament and the grid- The above statements as to the action of the device are the most plausible which at present can be given, but they are not intended in any manner to limit the invention which is defined in the appended claims.

What is claimed is: 1. In an electric system, an electric discharge device having spaced terminals therein between'which space current is adapted to flow, energizing circuits for said device normally closed, said device being normally lnoperative, and means comprising an elec- 115 trical conductor responsive to an impulse impressed on said device to render it operative, while permitting the connections for said circuits to remain fixed.

2. In an electric system, an electric discharge device, a source of voltage for said device, energizing circuits for said device normally closed, said device having normally zero space current flowing therein, and metallic means whereby an impulse received by said device establishes said current, while permitting the connections for said circuits to remain fixed.

3. In an electric system, an electric discharge devicehaving an input and an output circuit, a source of voltage for said output circuit, said device havin normally a given value of space current owing therein, and means comprising an electrical conductor whereby an impulse received by said device establishes a different value of said -zero space current flowing therein, and

metallic means whereby an impulse received by said device establishes said current which persists after said impulse has ceased.

5. In an electric system, an electric discharge device, a source of voltage for said device, energizing circuits for said device normally closed, said device being normally inoperative, and means comprising an electrical conductor whereby said device is made operative when an impulse is impressed on said device, while permitting the connections for said circuits to remain fixed.

6. The combination with an.electric discharge device, of an anode, a cathode and a control element within said device, energizing circuits for said device normally closed and means comprising an electrical conductor whereby said cathode is made independent of slow changes in the potential of said control element, said changes acting merely to cause a sudden rise of current in said device.

7. In an electric system, an electric discharge device having an anode, a cathode and an auxiliary electrode, means for establishing space current between said anode and said cathode, a source of voltage for said auxiliary electrode of sufficient value to reduce said space current to zero, and metallic means operative when said space current is flowing to prevent the static po-.

tential of said grid from modifying said space, current.

8. The combination with a vacuum tube discharge device Which is quantitatively responsive to high frequency variations, of means comprising a floating electrode associated with said device for changing said responsiveness from quantitative in nature to qualitative when the potential variations are of relatively low frequency.

9. In combination, an electric discharge device containing a cathode, an anode, a control electrode and a floating electrode, said floating electrode comprisin an apertured screen located between said cathode and said control electrode, and means for maintaining said control electrode and said anode at different potentials with respect to said cathode.

10. In an electric system, an electric dis charge device containing an anode, a cathode, a floating electrode, means comprising a fourth electrode for controlling said cathode, an electrical connection between said anode and cathode, an electrical connection be tween said fourth electrode and said cathode, and means for maintaining said fourth electrode and said anode at different potentials with respect to said cathode.

11. In an electric system, an electric discharge device containing an anode, a cathode, an aperture'd screen electrode, means comprising a fourth electrode for controlling said cathode, an electrical connection between said fourth electrode and said cathode, said screen electrode being disconnected from said other electrodes, and means for maintaining said anode and said fourth electrode at different potentials with respect to said cathode.

In witness whereof, I hereunto subscribe my name this 26th day of March, A. D.,

WILLIAM WILSON. 

